Title : A survivor of disseminated streptobacillus moniliformis infection complicated with aortic valve infective endocarditis, aortic root abscess and aortic pseudoaneurysm
Abstract:
Background: Streptobacillary endocarditis is rare and often associated with fatal complications. Since the year 2000, only twenty cases of endocarditis have been reported. Fifteen cases affected the mitral valve, while five cases involved the aortic valve. Two of the aortic valve endocarditis cases had aortic root abscess requiring surgical intervention, of which one survived and the other demised after. Our patient had infective endocarditis of the aortic valve, an aortic root abscess, and an aortic pseudoaneurysm. Additionally, the postoperative course was complicated by a complete heart block. The patient had an excellent recovery with antibiotics, surgery, and pacemaker implantation.
Case presentation: A previously healthy 56-year-old woman presented with 10 days history of fever, headache, ankle pains, and rash over the left ankle. She did not report any rodent bites. On admission, she was hemodynamically stable with no signs of infective endocarditis. Admission anaerobic blood culture showed gram-negative bacilli (figure 1), and after 6 days, Streptobacillus moniliformis was identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. On the seventh day of admission, diastolic murmur and collapsing pulse were noted. The echocardiogram showed severe aortic regurgitation with 0.8 cm vegetation, 1 cm perforation of the right coronary cusp, and aortic root wall abscess.
The computed tomography coronary angiogram showed a 2 x 2 cm pseudoaneurysm at the aortic root. On day fourteen of admission, she progressed to acute heart failure and cardiogenic shock requiring emergent debridement of periaortic abscess, patch repair of aortic root pseudoaneurysm, and aortic valve replacement (Figure 2). Intraoperative cultures were negative, histopathology was suggestive of infective endocarditis. Postoperatively, she developed a complete heart block and had dual chamber left bundle branch pacemaker implantation. She had an excellent recovery with 2 weeks of gentamicin and 4 weeks of crystalline penicillin from surgery.
Conclusions: Streptobacillary aortic valve infective endocarditis is rare and seems to be associated with aortic root complications of abscess and pseudoaneurysm formation requiring surgical intervention for good clinical outcomes. Diagnosis of Streptobacillary infection can be challenging due to its fastidious growth characteristic. Though our patient did not recollect any rodent bites, microbiological diagnosis, appropriate antimicrobial therapy, and surgical intervention contributed to our patient’s excellent outcome. Our case highlights the importance of rapid microbiological diagnostics to tailor appropriate antibiotics, close monitoring for infective endocarditis complications, and early surgical intervention as deemed necessary for good outcomes in such rare cases of Streptobacillary aortic valve infective endocarditis.
Keywords: Streptobacillary infective endocarditis
Audience Take Away:
- Streptobacillary infection is a rare zoonotic disease that is not commonly encountered. However, with the increasing popularity of domestic pet rodents, this infection has been emerging worldwide.
- Its clinical presentation is often unclear, and diagnostic confirmation is crucial to guide proper treatment.
- Diagnosing streptobacillary infection can be challenging due to its fastidious growth characteristics. Therefore, a thorough clinical and epidemiologic history, along with a high index of suspicion, is vital when dealing with gram-negative bacilli bacteremia. This approach will help guide physicians in tailoring their empiric antibiotics toward specific infections.
- Open communication between microbiologists and clinicians is vital for dealing with fastidious organisms. The introduction of molecular and PCR testing has overcome diagnostic challenges in fastidious organisms, guiding empiric treatment while awaiting organism identification.
- The organism's potential to cause abscesses and endocarditis increases its morbidity and mortality rates. However, this can be overcome with early diagnosis and appropriate antibiotic treatment.
- Despite a delay in diagnosis and appropriate treatment, which led to fatal complications, our patient survived with excellent recovery. Thus, early diagnosis of streptobacillary infection is crucial.
